This invention relates to aircraft undercarriages incorporating shock absorbing struts in which a resilient element, usually an enclosed quantity of gas, is loaded to absorb landing shocks by the action of liquid on a movable wall, the displacement of which varies the loading of the resilient element.
As well as absorbing the landing shocks, such aircraft undercarriages must also operate to smooth the ride of the aircraft during taxiing, and the desirable characteristics of the undercarriage are different in these two modes of operation. The absorption of landing shocks is the more important function of the undercarriage, such an undercarriage usually being designed to absorb the energy resulting from the vertical descent rate of the aircraft without causing excessive stresses in the structure and without causing the aircraft to bounce back into the air, but characteristics which are satisfactory under these conditions usually provide a hard ride during taxiing. Some attempts have been made to overcome this disadvantage and provide modified characteristics in the taxiing mode, but it is believed that previous proposals are not completely satisfactory in providing the best ride comfort with minimum induced airframe stresses during taxiing.